Objective:Toevaluatetherolesofischemiaandhypoxiainthedevelopmentofpost-burncardiacshockanditsmolecularpathogenesis. Methods: One hundred and fifty healthy adult Wistar rats were divided into the control group and burn group inflicted with 30% total body surf acearea third degree burn. Groups were processed at 1, 3, 6, 12 and 24 hpost-burn. Myocardial contractile function, myocardial microvascular permeability, volume of regional myocardial bloodflow, levels of myocardial myosin light chain1 (CM-LC1), myocardial NF-B(nuclear factor kappa B)activity, MPO(myeloperoxidase), TNF (tumor necrosis factor)mRNA expression and level sofmyocar- dialTNFweremeasured.Mainresults:Myocardialmicrovascularpermeabilitybegantoriseat1hpost-burnandwasstillrisingat24h(2.1 timesashighasthatofthecontrolgroup);thevolumeofregionalmyocardialbloodflowfellsignificantlyandremainedatalevelmarkedly lower than that in the control group; CM-LC1 also rose significantly and reached a level 18.6 times as high as that in the control group; myocardialNF-BactivityandTNFmRNAexpressionweresignificantlypromoted;elevationoflevelsofmyocardialTNFandMPO activityoccurred;cardiacmechanicparametersincludingLVSP,